Just when we may have started to hope that the excesses of Donald Trump’s campaign will give way to a more sober and reasonable mode of behavior once in office, the president-elect has a way of lurching back to the familiar excesses, usually with an outburst on Twitter.  This past weekend it was his return to the Big Lie with the accusation that millions of people voted illegally in this month’s election.  It was an assertion so far removed from truth that the New York Times dispensed with journalistic political correctness and described the assertion correctly and accurately in a headline as “baseless”.

Maybe Trump was calculatedly laying groundwork for the enactment at the state level of additional voter suppression laws.  Maybe it was another instance of his using an attention-getting blurt to attract attention away from other matters, such as disarray in his transition operation or conflict-of-interest issues involving his business interests.  More likely it was a less calculated and less controlled lashing out by a notoriously thin-skinned man who abhors losing and has been seeing his losing popular vote margin grow to well over two million votes—without regard to how such a lashing out assists Russian efforts to discredit the workings of American democracy.   

There are many other sad things that could be said about the consequences for those workings of having a leader with so little regard for truth, which encourages further entrenchment of falsehood in politics and public affairs.  In this respect Trump is both a symbol and arch-facilitator of a malevolent trend that led the Oxford English Dictionary to make “post-truth” its word of the year.

But consider for the moment one significant consequence for U.S. foreign relations: the greater disinclination of foreign governments and peoples to believe what the United States says.  A significant ingredient of the pursuit of U.S. interests abroad is being weakened.  Daniel Drezner has explained part of the problem, citing John Mearsheimer's research on lying by leaders and how they usually have good reason not to lie to other governments, and how credible commitment is a key component of deterrence.  But it is not just deterrence, and keeping others from doing what we don’t want them to do, that is involved.  Being able to make credible promises, and getting others to do what we want them to do as part of cooperative arrangements, also requires others to believe that one’s leader speaks truthfully and has every intention of following through on positive commitments.  Here Trump’s record of lying complements in the most deleterious way his business record of repeatedly stiffing vendors and sub-contractors—another habit of his that does not appear to be ending.

A fundamental underlying fact about the exercise of U.S. power overseas is that most of the time it is exercised not by the United States directly, physically doing things.  Most of the time its exercise involves other states perceiving the U.S. ability to do certain things and believing it will do those things under certain conditions.  That in brief is why credibility matters.

At stake is not just the reputation of any one occupant of the White House.  The credibility of the U.S. president affects the credibility of the United States.  And the perceptions that matter are those held not only by foreign governments but also by foreign publics.  A reputation for lying by the person at the top exacerbates what are already widespread and unhelpful tendencies of many people overseas not to believe what the United States says are its reasons for its actions overseas.  This is especially a problem in the Muslim world; in this instance with Trump, the deleterious complementarity is between his lying and his Islamophobia.

The threat to U.S. credibility involved here is far more real than the supposed threat that often is posited: that if the United States does not immerse itself in this or that conflict that is peripheral to its interests, then other governments will not believe that the United States will stand up for its interests elsewhere.  That is not how governments calculate credibility.  U.S. credibility depends not on intervening in what is peripheral but instead on U.S. leaders being believed when they say something is vital.